US5274563A - Noncontact tracing control system - Google Patents

Noncontact tracing control system Download PDF

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Publication number
US5274563A
US5274563A US07/855,003 US85500392A US5274563A US 5274563 A US5274563 A US 5274563A US 85500392 A US85500392 A US 85500392A US 5274563 A US5274563 A US 5274563A
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United States
Prior art keywords
points
noncontact
tracing
control system
distance
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Expired - Fee Related
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US07/855,003
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English (en)
Inventor
Hitoshi Matsuura
Eiji Matsumoto
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Fanuc Corp
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Fanuc Corp
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Assigned to FANUC LTD., A CORP. OF JAPAN reassignment FANUC LTD., A CORP. OF JAPAN ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MATSUMOTO, EIJI, MATSUURA, HITOSHI
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q35/00—Control systems or devices for copying directly from a pattern or a master model; Devices for use in copying manually
    • B23Q35/04—Control systems or devices for copying directly from a pattern or a master model; Devices for use in copying manually using a feeler or the like travelling along the outline of the pattern, model or drawing; Feelers, patterns, or models therefor
    • B23Q35/08—Means for transforming movement of the feeler or the like into feed movement of tool or work
    • B23Q35/12—Means for transforming movement of the feeler or the like into feed movement of tool or work involving electrical means
    • B23Q35/127—Means for transforming movement of the feeler or the like into feed movement of tool or work involving electrical means using non-mechanical sensing
    • B23Q35/128—Sensing by using optical means
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/41—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path

Definitions

  • the present invention relates to a noncontact tracing control system, and more particularly, to a noncontact tracing control system with an improved tracing accuracy.
  • a recently developed noncontact tracing control system utilizing a noncontact distance detector for tracing the contour of a model uses an optical distance detector fixed at the tip end of a tracer head and detecting a distance to the model surface, for a tracing thereof. This system eliminates worry about damage to the model, and therefore, a soft material model can be used, and thus the applicability thereof in tracing machining is expected to expand.
  • the conventional noncontact tracing control system has a problem in that the tracing accuracy is low at portions of a model where an inclination thereof is large. Namely, in such a portion, an optical measuring axis of a distance detector becomes almost parallel to the model surface, whereby a spot on the model surface is expanded and becomes an ellipsoid, and thus the resolution of the distance detector is lowered, and accordingly, the tracing accuracy also is lowered. Particularly for a trigonometrical distance detector, a measurement sometimes becomes impossible because, depending on this angle, the optical measuring axis interferes with the model surface.
  • the present invention has been made in view of the aforesaid drawbacks, and an object of the present invention is to provide a noncontact tracing control system whereby points needed for acquiring a normal vector of an accurate model surface can be selected.
  • a noncontact tracing control system for tracing machining a workpiece through a tracing of the contour of a model without a contact therewith, comprising first and second noncontact distance detectors inclined by a certain angle to a predetermined straight axis, respectively, and attached to a tracer head controlled by the straight axis and a rotation axis rotated around the straight axis, to thereby measure the distance to the model surface without a contact therewith, respectively, a sampling means for sampling measured values of the above respective distance measured by the first and second noncontact distance detectors at predetermined sampling times, a memory means for storing the measured values obtained by the first noncontact distance detector and the second noncontact distance detector and sampled at a plurality of times of sampling, a point selecting means for selecting three points forming a triangle that is closest to an equilateral triangle, from the measured values, a vector calculating means for calculating a normal vector on the model surface based on the measured values of
  • Coordinate values of a plurality of points on the model surface are acquired from the measured values obtained at a plurality of times of sampling, from the two noncontact distance detectors provided at the tracer head, and from these values, the three points forming a triangle closest to an equilateral triangle are selected.
  • a normal vector is acquired using the coordinate values of the vortices of these three points, and the tracer head is rotated in the direction of the projection of this normal vector onto the X-Y plane. Accordingly, as the measuring axes of the noncontact distance detectors are oriented in the direction most nearly perpendicular to the model surface, the distance to the model surface can be measured with a high accuracy.
  • FIG. 1 is a block diagram showing the constitution of a noncontact tracing control system according to an embodiment of the present invention
  • FIG. 2 is a detailed view of a tracer head in a preferred embodiment of the present invention.
  • FIG. 3 is an explanatory view of a method of calculating a rotation angle of a tracer head in a preferred embodiment of the present invention
  • FIG. 4 is a flow chart of a calculation of a rotation angle in a preferred embodiment of the present invention.
  • FIG. 5 is an explanatory view of a point selecting means for selecting three points forming a triangle closest to an equilateral triangle.
  • FIG. 1 is a block diagram showing a noncontact tracing control system and associated peripheral equipment according to the present invention.
  • a processor 11 reads a system program stored in a ROM 12 through a bus 10, and controls the overall operation of a noncontact tracing control system I according to this system program.
  • a RAM 13 temporarily stores data, and stores measured values obtained from distance detectors, described later, and other temporary data.
  • a nonvolatile memory 14 is backed up by a battery, not shown, and stores various parameters such as a tracing direction, tracing speed, etc., input from a control panel 2 through an interface 15.
  • Distance detectors 5a and 5b are provided at a tracer head 4 of a tracing machine 3. Reflected light amount type distance detectors using a semiconductor laser or a light emitting diode as a light source are utilized for the distance detectors 5a and 5b, which are able to measure the distance to a model 6 without contact therewith. These distances la and lb are converted to digital values by A/D converters 16a and 16b in the noncontact tracing control system 1, and are sequentially read by the processor 11.
  • the processor 11 calculates the amounts of displacement of each axis, based on the measured values la and lb, and signals from present position registers 19x, 19y, and 19z, described later, and generates speed commands Vx, Vy, and Vz of the respective axes based on these amounts of displacement, the commanded tracing direction, and the tracing speed, according to a known process.
  • These speed commands are converted to digital values by D/A converters 17x, 17y, and 17z and input to servo amplifiers 18x, 18y, and 18z.
  • the servo amplifiers 18x and 18y drive servo motors 32x and 32y of the tracing machine 3, based on these speed commands, to thereby move a table 31 in the X-axis direction and the Y-axis direction at a right angle to the paper surface. Also, the servo amplifier 18z drives a servo motor 32z, to thereby move the tracer head 4 and the toot 34 in the Z-axis direction.
  • Pulse coders 33x, 33y, and 33z are provided in the servo motors 32x, 32y, and 32z for generating detection Pulses FPx, FPy, and FPz upon a rotation by a predetermined amount of these servo motors.
  • the present position registers 19x, 19y, and 19z in the noncontact tracing control system 1 acquire present position data Xa, Ya, and Za in each axial direction by counting up/down the detection Pulses FPx, FPY, and FPz according to the respective direction of rotation and inputs same to the processor 11.
  • the processor 11 samples the distances la and lb measured by the distance detectors 5a and 5b at predetermined sampling times, simultaneously with the control of the above respective axes, acquires a normal vector on the surface of the model 6 by the method of using this sampling data, described later, and generates a rotation command SC corresponding to the direction of a projection of the normal vector onto the X-Y plane.
  • the rotation command SC is converted to a digital value by the D/A converter 17c and input to the servo amplifier 18c, and based on this command, the servo amplifier 18c drives a servo motor 32c of the C axis.
  • the tracer head 4 is rotated by the commanded angle and controlled in such a manner that a distance, described later, from the model 6 is kept constant.
  • the table 31 is moved in the commanded tracing direction at the commanded tracing speed, and a workpiece 35 is machined to the same shape as that of the model 6 by the toot 34 controlled in the Z-axis direction, as the tracer head 4.
  • FIG. 2 is a detailed view of the tracer head 4.
  • the distance detector 5a is mounted on the tracer head 4 and is inclined by angle ⁇ to the Z-axis, and rotated by the C-axis along the circumference of a predetermined radius at a commanded angle ⁇ c of t he rotation command SC.
  • the distance detector 5b is mounted on the outside of the distance detector 5a, and is similarly rotated and controlled at the angle of the commanded angle ⁇ c.
  • the distance la from the distance detector 5a to a point of measurement P1 on the model 6 is kept constant. Also, this distance la is set at the distance to the point of an intersection of the measuring axes of the distance detector 5a and the Z-axis, and therefore, even when the tracer head 4 is rotated by the C-axis, the measurement point P1 is not moved, i.e., the distance l from the tracer head 4 to the model 6 is also kept constant.
  • the distance detector 5b measures the distance lb to a point of measurement P2 on the model 6 and inputs same to the tracing control system.
  • tracing is carried out by moving the tracer head 4 relative to the model 6 in the X-axis direction at a predetermined speed, measured values obtained by the distance detectors 5a and 5b are sampled at predetermined times, and coordinate values of the points P1 1 , . . . , P1 n-1 , P1 n , and P2 1 , . . . , P2 n-1 , P2 n on the model 6 are acquired based on these measured values and the present position data output from the present position registers.
  • a surface vector S1n [X2 n -X1 n , Y2 n -Y1 n , Z2 n -Z1 n ] is acquired from the coordinate values of the point P1 n (X1 n , Y1 n , Z1 n ) and the coordinate values of the point P2 n (X2 n , Y2 n , Z2 n ).
  • a surface vector S2n [X1 n-1 -X1 n , Y1 n-1 -Y1 n , Z1 n-1 -Z1 n ] is acquired from the coordinate values of the point P1 n (X1 n , Y1 n / Z1 n ) and the coordinate values of the point P1 n-1 (X1 n-1 , Y1 n-1 , Z1 n-1 ).
  • angle ⁇ cn made by a projection N1n of the normal vector Nn projected onto the X-Y plane and the X-axis is acquired by the following equation, and that angle ⁇ cn is out put as a command value of the C axis:
  • This angle is changed in accordance with an inclination of the model 6 to, for example, ⁇ cq at point P1q.
  • the measuring axis of the distance detector is oriented in the direction most nearly perpendicular to the surface of the model 6, to thereby obtain a distance measurement with a high accuracy.
  • FIG. 4 is a flow chart of the calculation of the rotation angle in a preferred embodiment of the present invention.
  • the numerical values following the letter S represent step numbers.
  • a normal vector N is acquired by calculating a vector product of the vector S1 and the vector S2.
  • FIG. 5 is an explanatory view of the point selecting means for selecting the three points forming a triangle closest to an equilateral triangle.
  • the present measurement point obtained by the distance detector 5a is made P1, the previous measurement point made P11, and the measurement point before last made P12, respectively. These points correspond to the points P1 n , P1 n-1 , . . . in FIG. 3.
  • the present measurement point obtained by the distance detector 5b is made P2, the previous measurement point made P21, and the measurement point before last made P22, respectively. These points correspond to the points P2 n , P2 n-1 , . . . in FIG. 3.
  • the measurement points P1 and P11 of the distance detector 5a are selected as two points, and then the point forming a triangle closest to an equilateral triangle is selected from among the points P2, P21, and P22.
  • three triangles i.e., the triangle formed by P1, P11 and P2, the triangle formed by P1, P11 and P21, and the triangle formed by P1, P11 and P22, are considered.
  • the distance between the point P1 and the point P11 is made A
  • the distances between the point P1 and the point P2, the point P21 and the point P22 are made B1, B2, and B3, respectively
  • the distances between the point P11 and the point P2, the point P21, and the point P22 are made C1, C2, and C3, respectively.
  • the first two points are the present measurement point and the previous measurement point of the distance detector 5a
  • the measurement is not limited to those points as the present measurement points of the distance detectors 5a and 5b also may be used.
  • an optical trigonometrical type, an eddy current type or an ultrasonic type distance detector also can be used for the distance detector.
  • the present invention as described above, as three points forming a triangle closest to an equilateral triangle are selected from among a plurality of measurement points obtained from two noncontact distance detectors provided at the tracer head, a normal vector of the model surface is acquired based on the measured values, and the tracer head is rotated and controlled in the direction of a projection of this normal vector onto a predetermined plane, the measuring axis of the noncontact distance detector is oriented in the direction most nearly perpendicular to the model surface at all times, and accordingly, a distance measurement with a high accuracy is obtained, and thus the tracing accuracy is improved.

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  • Engineering & Computer Science (AREA)
  • Automation & Control Theory (AREA)
  • Manufacturing & Machinery (AREA)
  • Computing Systems (AREA)
  • Theoretical Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Machine Tool Copy Controls (AREA)
  • Numerical Control (AREA)
  • Length Measuring Devices With Unspecified Measuring Means (AREA)
  • Length Measuring Devices By Optical Means (AREA)
US07/855,003 1990-09-07 1991-08-23 Noncontact tracing control system Expired - Fee Related US5274563A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2-238058 1990-09-07
JP2238058A JPH04115854A (ja) 1990-09-07 1990-09-07 非接触ならい制御装置

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US5274563A true US5274563A (en) 1993-12-28

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US07/855,003 Expired - Fee Related US5274563A (en) 1990-09-07 1991-08-23 Noncontact tracing control system

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US (1) US5274563A (de)
EP (1) EP0506966B1 (de)
JP (1) JPH04115854A (de)
DE (1) DE69111421T2 (de)
WO (1) WO1992004157A1 (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5343402A (en) * 1991-02-06 1994-08-30 Fanuc Ltd. Non-contact digitizing control unit
US5550330A (en) * 1991-10-16 1996-08-27 Fanuc Limited Digitizing control apparatus
US6212442B1 (en) * 1995-12-05 2001-04-03 Nobel Biocare Ab Compressing device in association with a dental product or other product related to the human body, or tool for this product
US20050203660A1 (en) * 2004-03-10 2005-09-15 Fanuc Ltd Machining apparatus
US20060206233A1 (en) * 2005-03-09 2006-09-14 Carpenter David A Method and apparatus for cutting a workpiece
US20090033271A1 (en) * 2007-07-31 2009-02-05 Fanuc Ltd Machine tool having function of correcting mounting error through contact detection
US20150338839A1 (en) * 2014-05-20 2015-11-26 Caterpillar Inc. System to verify machining setup

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6076953A (en) * 1995-10-10 2000-06-20 The Esab Group, Inc. Digitizing probe

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61274852A (ja) * 1985-05-28 1986-12-05 Agency Of Ind Science & Technol 非接触曲面ならいセンサ
JPS6464753A (en) * 1987-09-02 1989-03-10 Fanuc Ltd Noncontact copying method
JPH01109058A (ja) * 1987-10-23 1989-04-26 Fanuc Ltd 非接触ならい制御装置
JPH01188254A (ja) * 1988-01-19 1989-07-27 Fanuc Ltd 非接触倣いデジタイジング方法
JPH01313801A (ja) * 1988-06-14 1989-12-19 Ichikoh Ind Ltd プロジェクタ型前照灯
JPH033760A (ja) * 1989-05-30 1991-01-09 Fanuc Ltd デジタイジング制御装置
JPH0360956A (ja) * 1989-07-27 1991-03-15 Fanuc Ltd 非接触ならい制御装置
US5015130A (en) * 1987-06-19 1991-05-14 Fanuc Ltd. Contour profiling machine
JPH03121754A (ja) * 1989-10-04 1991-05-23 Fanuc Ltd 非接触ならい制御装置
US5019993A (en) * 1987-10-26 1991-05-28 Advanced Data Processing Adp S.R.L. Machine for measuring and mathematically defining the surface of three-dimensional models, particularly for the manufacture of molds with numeric-control machine tools

Family Cites Families (2)

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Publication number Priority date Publication date Assignee Title
JPS61274853A (ja) * 1985-05-28 1986-12-05 Shin Meiwa Ind Co Ltd 罫書き線追従装置
JPS6215063A (ja) * 1985-07-10 1987-01-23 Shin Meiwa Ind Co Ltd 罫書き線追従装置における距離、姿勢制御装置

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61274852A (ja) * 1985-05-28 1986-12-05 Agency Of Ind Science & Technol 非接触曲面ならいセンサ
US5015130A (en) * 1987-06-19 1991-05-14 Fanuc Ltd. Contour profiling machine
JPS6464753A (en) * 1987-09-02 1989-03-10 Fanuc Ltd Noncontact copying method
JPH01109058A (ja) * 1987-10-23 1989-04-26 Fanuc Ltd 非接触ならい制御装置
US5019993A (en) * 1987-10-26 1991-05-28 Advanced Data Processing Adp S.R.L. Machine for measuring and mathematically defining the surface of three-dimensional models, particularly for the manufacture of molds with numeric-control machine tools
JPH01188254A (ja) * 1988-01-19 1989-07-27 Fanuc Ltd 非接触倣いデジタイジング方法
JPH01313801A (ja) * 1988-06-14 1989-12-19 Ichikoh Ind Ltd プロジェクタ型前照灯
JPH033760A (ja) * 1989-05-30 1991-01-09 Fanuc Ltd デジタイジング制御装置
US5182714A (en) * 1989-05-30 1993-01-26 Fanuc Ltd. Digitizing control apparatus
JPH0360956A (ja) * 1989-07-27 1991-03-15 Fanuc Ltd 非接触ならい制御装置
US5140239A (en) * 1989-07-27 1992-08-18 Fanuc Ltd. Non-contact tracer control device
JPH03121754A (ja) * 1989-10-04 1991-05-23 Fanuc Ltd 非接触ならい制御装置

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5343402A (en) * 1991-02-06 1994-08-30 Fanuc Ltd. Non-contact digitizing control unit
US5550330A (en) * 1991-10-16 1996-08-27 Fanuc Limited Digitizing control apparatus
US6212442B1 (en) * 1995-12-05 2001-04-03 Nobel Biocare Ab Compressing device in association with a dental product or other product related to the human body, or tool for this product
US20050203660A1 (en) * 2004-03-10 2005-09-15 Fanuc Ltd Machining apparatus
US7082349B2 (en) * 2004-03-10 2006-07-25 Fanuc Ltd Machining apparatus for machining a workpiece to reproduce a model shape
US20060206233A1 (en) * 2005-03-09 2006-09-14 Carpenter David A Method and apparatus for cutting a workpiece
US20090033271A1 (en) * 2007-07-31 2009-02-05 Fanuc Ltd Machine tool having function of correcting mounting error through contact detection
US7852031B2 (en) * 2007-07-31 2010-12-14 Fanuc Ltd Machine tool having function of correcting mounting error through contact detection
US20150338839A1 (en) * 2014-05-20 2015-11-26 Caterpillar Inc. System to verify machining setup

Also Published As

Publication number Publication date
EP0506966B1 (de) 1995-07-19
DE69111421D1 (de) 1995-08-24
JPH04115854A (ja) 1992-04-16
EP0506966A4 (de) 1992-08-10
DE69111421T2 (de) 1996-01-04
WO1992004157A1 (en) 1992-03-19
EP0506966A1 (de) 1992-10-07

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